Automatic pilot valve magnet contact construction

ABSTRACT

A pilot valve assembly including a valve controlling electromagnet within a housing which is enclosed by a conductive supporting base for the electromagnet. The supporting base includes a cavity therethrough for accommodating an insulated conductive contact member therein which has one end electrically connected within the housing to a coil of the electromagnet and the other end adapted to be connected to a thermocouple when threaded into the cavity.

United States Patent 1 1 1111 3,810,054 Nelson May 7, 1974 [54] AUTOMATIC PILOT VALVE MAGNET 2,976,345 3/1961 Whitted 339/126 RS x CONTACT CONSTRUCTION 3,268,650 8/1966 Hepker 339/126 RS X 3,261,909 7/1966 Rust et al 339/126 RS X [75] Inventor: Rodney Nelson, Los Angeles,

I Cahf' Primary ExaminerGeorge Harris [73] Assignee: Robertshaw Controls Company, Attorney, Agent, or Firm-Anthony A. OBrien Richmond, Va.

[22] Filed: I Apr. 26, 1973 [57] ABSTRACT [2 Appl- 354,576 A pilot valve assembly including a valve controlling electromagnet within a housing which is enclosed by a 52 US. Cl 335/220 137/66 139/126 RS cmductive SUPPOmIg base electmmagnet- [51] Int. Cl. HOlf 7/08 The Supportingbase includes a cavity therthmugh for 58 Field of Search 335/281, 220; 137/66; accommodating an insulated conductive Contact 339/89 126 236/21 ber therein which has one end electrically connected within the housing to a coil of the electromagnet and [56] References Cited the other end adapted to be connected to a thermo- UNITED STATES PATENTS couple when threaded into the cavity.

3,258,659 6/1966 Schmid et al. 335/220 10 Claims, 6 Drawing Figures AUTOMATIC PILOT VALVE MAGNET CONTACT CONSTRUCTION BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to pilot valve assemblies utilized as control devices in heating appliances such as hot water heaters and more particularly to an insulated contact structure employed therein.

2. Description of the Prior Art In heating appliances such as hot water heaters, the use of a pilot valve assembly for terminating flow of fuel to both a main burner and a pilot burner in the event the pilot light extinguishes is a common expedient, as typified in U.S. Pat. Nos. 3,286,216 and 3,286,923. In the use of such pilot valve assemblies, a valve member associated with an armature that is biased to a valve closing position is retained in a valve opening position by an electromagnet when energized by a thermocouple responding to the flame at the pilot burner. The thermocouple is threaded into a magnet support base of the pilot valve assembly with electrical connections to a coil of the electromagnet made through the threads and through the center wire lead tip of the thermocouple contacting the contact member in the magnet support base. A problem has resulted with these pilot valve assemblies due to the fact that torquing the thermocouple into the magnet support base has a tendency to rotate the contact and has resulted in some cases in breakage of the coil wire connection thereto through twisting of the wire.

Another problem in such pilot valve assemblies relates to the high fabrication cost due to the use of a relatively expensive molded insulator for the contact, which is specially constructed at high cost and accordingly requires special handling during fabrication which also adds to the cost of the overall product.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to construct a pilot valve assembly having a durable contact structure.

It is another object of the present inventionto provide a pilot valve assembly with a contact structure having a high resistance to rotation.

It is still another object of the present invention to produce a pilot valve assembly having a simplified contact member insulation structure.

The present invention is summarized in an electromagnetic assembly including a housing, a supporting base for the housing having a portion defining a cavity therein, electromagnetic means including a coil disposed on the supporting base within the housing, con ductor means electrically connected to the coil of the electromagnetic means and having a portion extending into the cavity defined in the supporting base, insulating means abutting the periphery of the conductor means within the cavity, and means defining at least one gripping flute on the periphery of the conductor means which extends into the cavity.

Other objects and advantages of the present ivnention will be more fully apparent from the following description of the preferred embodiments when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevation view partially in cross section of a pilot valve assembly in accordance with the present invention installed in a fuel flow line;

FIG. 2 is a side elevation view partially in cross section with parts broken away of the pilot valve assembly of FIG. 1;

FIG. 3 is a side elevation view in partial cross section of a detail of FIG. 2 on an enlarged scale;

FIG. 4 is a side elevation view in partial cross section of a detail of FIG. 3 on an enlarged scale;

FIG. 5 is a cross section view taken along the line 55 of FIG. 4 of a fluted contact member employed in the pilot valve assembly in accordance with the present invention; and

FIG. 6 is a side elevation view in cross section of an alternative embodiment of a magnet support base for use in the pilot valve assembly of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As illustrated in FIG. 1, the present invention is em- I bodied in an electromagnetic pilot valve assembly, generally indicated at 10, shown disposed in a control device 12 having a fuel flow line therethrough including an inlet port 14, an outlet port 16 and a valve seat 18 therebetween. The electromagnetic assembly 10 includes a generally cylindrical magnet housing 20 having an axially disposed boss 22 which is axially bored to receive a movable valve stem 24 therethrough which extends out of housing 20 to a position proximate valve seat 18. Valve stem 24 has a valve head assembly at its end proximate valve seat 18 which includes a rigid hat shaped plate member 26 supporting a resilient seating ring 28 thereon which may be rubber, for example. A v

bias spring 30 is coiled about valve steam 24 and is disposed in compression between housing 20 and plate member 26. The end of valve stem 24 disposed within housing 20 has a ferromagnetic armature 40 affixed thereto, as shown in FIG. 2, which is positioned proximate an electromagnet 42. A cylindrical magnet support base 44, which is made from an electrically conductive material, is circumferentially sealed to housing 20 at 46. The magnet support base 44 forms an enclosing wall to said housing and additionally supports electromagnet 42 thereon.

With reference to FIG. 3, magnet support base 44 has an externally screw threaded portion 60 and a hexagonal shaped head 62. A centrally disposed bore 64 extends completely through magnet support base 44 and includes a small diameter portion 66 proximate electromagnet 42 and a larger diameter portion 68 having internal screw threads 70 along a portion thereof. An annular seal 71 extending from magnet support base 44 directly supports electromagnet 42 thereon in a central position relative to bore 64.

The electromagnet 42 includes a generally U-shaped ferromagnetic core 72 centrally located with respect to bore 64 and annular seal 71. Ferromagnetic core 72 has a bore 74 therein coaxially disposed relative to bore 64 and having a smaller diameter than that of the small diameter portion 66 of bore 64. A pair of coils 76 and 78 interconnected at one end are wound around respective legs of core 72 in a flux aiding direction. Coil 76 has its free end 80 electrically connected to magnet support base 44 while coil 78 has its free end 82 electrically connected at two places to the rim of an electrically conductive contact member 84 disposed within bore 74 and extending into bore 64.

As best shown in FIG. 4, the conductive contact member 84 includes a generally cylindrical upper portion 96 having a flared end 98, and an intermediate cylindrical portion 100 of greater diameter than upper portion 96 and joined thereto by a frusto-conical portion 102. The intermediate portion 100 includes a plurality of axially aligned gripping flutes 104 disposed about its outer periphery. The flutes 104 take the form of V-shaped grooves, best shown in FIG. 5, each of which extends from a position near the bottom of intermediate portion 100 into the frusto-conical portion 102. A cylindrical contact head 106 having a tapered recess 108 therein 100.

An insulating washer 110, which may be of sheet stock nylon, for example, is disposed about intermediate portion 100 and rests upon cylindrical contact head 106. An insulating sleeve 112 which extends between the flared end 98 of upper portion 96 and washer 110 has an internal surface contoured to frictionally mate with the outer cylindrical surfaces of the upper portion 96 and intermediate-portion 100 of contact member 84. Sleeve 112 may be any type of insulating material having sufficient resilience to accept the fluted contact member 84 and still maintain its insulation integrity, such as commercially available nylon tubing. The outer surface of sleeve 1l2 is frictionally fitted in the small diameter portion 66 of magnet support base 44 and bore 74 of ferromagnetic core 72.

In the alternative embodiment shown in FIG. 6, the small diameter portion 66 of bore 64 in the magnet support base 44 may also include a plurality of axially aligned flutes 120 in the surface thereof. These flutes 120, which extend the entire length "of the small diameter portion 66, may be V-shaped grooves similar to the flutes 104 in contact'member 84, but directed radially outward to establish discontinous gripping surfaces which frictionally engage insulating sleeve 112 and contact member 84'therein.

During assembly; the insulating washer 110 is slid over upper portion 96 of contactmember 84, which initially is not flared at its upper end and is fitted about the intermediate portion 100 such that it abuts the adjacent surface of contact head 106. The insulating sleeve 112 is then inserted over the upper portion 96 and intermediate portion 100 to abut insulating washer 110. The relative dimensions between the inner surface of insulating sleeve 112 and the outer surface of depends from intermediate portion 7 contact member 84 encompassed thereby are such as to establish a snug fit therebetween when assemblied. The thus insulated contact member 84 is inserted through bore 74 of electromagnetic core 72 and is snugly fitted into bore 66 of magnet support base 44 and is staked in place by deforming the end of upper portion 96 to form the flared end 98 over electromagnetic core 72 with a portion of insulator sleeve 112 likewise deformed therebetween.

The interconnected coils 76 and 78 are then disposed on the respective legs of electromagnetic core 72 and the free ends thereof are welded to the flared end 98 of contact member 84 and the magnet support base 44, respectively. The housing 20 and associated valve structure extending therethrough may then be fitted and sealed to the magnet support base 44.

When a thermocouple is thereafter torqued into the magnet support base 44 to establish electrical contact with the tapered recess 108 in contact head 106, the gripping flutes 104 offer a high resistance to any rotational forces transmitted from the thermocouple to contact member 84 via contact head 106, thereby effectively preventing rotation of contact member 84 and preserving the intergrity of the welded connection of coils 76 and 78 thereto.

The pilot valve assembly disclosed is advantageous in that the use of the fluted contact member 84 has the effect of materially increasing the force necessary to cause rotational slippage between the contact member 84 and the coils 76 and 78 of electromagnet 42, which practically eliminates breakage of the connection therebetween due to contact rotation upon installation of the thermocouple. In addition, an appreciable cost saving results from using commercially available nylon tubing for the sleeve and sheet stock nylon for the washer rather than the specially constructed molded nylon insulators of the prior art, the use of which increases the possibility of further costsaving in that these insulator parts lend themselves to installation with an automatic assembly machine.

Inasmuch as the present invention is subject to many variations,modifications and changes in detail, it is intended that all matter contained in the foregoing description or shownin the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is: Y t

1. An electromagnetic assembly comprising:

a housing; Y

a supporting base for said housing having a portion defining a cavity therein; electromagnetic means including a coil and disposed on said supporting base within said housing; conductor means electrically connected to the coil of said electromagnetic means and having a portion extending into the cavity defined in said supporting base; I I insulating means abutting the periphery of said conductor means within said cavityyand y means defining at least one gripping flute on the periphery of said conductor means which extends into said cavity. i

2. The invention of claim 1 wherein said cavity and said portion of the conductor means extending therein are cylindrical, and wherein said insulating means includes acylindrical sleeve frictionally fitted therebetween.

3. The invention of claim 2 wherein said cavity includes a small diameter cylindrical portion containing said cylindrical portion of said conductor means and said insulating sleeve, and a larger diameter cylindrical portion, and wherein said conductor means includes an enlarged cylindrical contact head in. said larger diameter cylindrical portion.

4. The invention of claim 3 wherein said insulating means includes an insulating washer disposed about said conductor means between said insulating sleeve and'said contact head.

5. The invention of claim 4 wherein said small diameter cylindrical portion of said cavity in said supporting base includes means defining a plurality of axially aligned gripping flutes in the periphery thereof.

means in said cavity.

9. The invention of claim 1 wherein the cavity of said supporting base includes means defining at least one gripping flute on the periphery thereof.

10. The invention of claim 5 wherein said at least one gripping flute comprises a plurality of gripping flutes axially aligned about said supporting base. 

1. An electromagnetic assembly comprising: a housing; a supporting base for said housing having a portion defining a cavity therein; electromagnetic means including a coil and disposed on said supporting base within said housing; conductor means electrically connected to the coil of said electromagnetic means and having a portion extending into the cavity defined in said supporting base; insulating means abutting the periphery of said conductor means within said cavity; and means defining at least one gripping flute on the periphery of said conductor means which extends into said cavity.
 2. The invention of claim 1 wherein said cavity and said portion of the conductor means extending therein are cylindrical, and wherein said insulating means includes a cylindrical sleeve frictionally fitted therebetween.
 3. The invention of claim 2 wherein said cavity includes a small diameter cylindrical portion containing said cylindrical portion of said conductor means and said insulating sleeve, and a larger diameter cylindrical portion, and wherein said conductor means includes an enlarged cylindrical contact head in said larger diameter cylindrical portion.
 4. The invention of claim 3 wherein said insulating means includes an insulating washer disposed about said conductor means between said insulating sleeve and said contact head.
 5. The invention of claim 4 wherein said small diameter cylindrical portion of said cavity in said supporting base includes means defining a plurality of axially aligned gripping flutes in the periphery thereof.
 6. The invention of claim 1 wherein said insulating means includes a sleeve about said conductor in said cavity and extending into said housing.
 7. The invention of claim 6 wherein said insulating means includes a washer disposed about said conductor means.
 8. The invention of claim 1 wherein said at least one gripping flute comprises a plurality of gripping flutes in axial alignment about the portion of said conductor means in said cavity.
 9. The invention of claim 1 wherein the cavity of said supporting base includes means defining at least one gripping flute on the periphery thereof.
 10. The invention of claim 5 wherein said at least one gripping flute comprises a plurality of gripping flutes axially aligned about said supporting base. 